no. 1617. NEW CRETACEOUS AND TERTIARY FOSSILS—ARNOLD. « 369 
tinct, appressed, and just overlapping the lower keel of the ante- 
cedent whorl; aperture subpyriform ; canal moderately long, tapering 
quite rapidly forward. 
Dimensions.—Of type, from which a portion of the spire is re- 
moved, length, 24 mm.; latitude, 13 mm. 
Notes.—The type of this species is a fairly well preserved mold of 
the penultimate and body whorls (locality No. 107) ;the figure 1s of 
a wax cast from the mold; another specimen of the same species from 
locality No. 101 retains a portion of the original shell material and 
furnishes the detailed characters of the external sculpture. P. per- 
issolaxoides reminds one of the young of the living P. cércinata Dall 
from Alaska, but differs from the latter in having a minor keel on the 
body whorl. Named for its general resemblance to Perissolax blaket 
Conrad from the Kocene of California. 
Type.—Cat. No. 165451, U.S.N.M. (Locality No. 107.) 
[Torizzon.—San Lorenzo formation, Oligocene. 
Localities.—Santa Cruz quadrangle, Santa Cruz County, locality 
No. 101, on San Lorenzo River about 33 miles above Boulder Creek ; 
locality 107, small ravine off Boulder Cre&k about 24 miles north of 
Kagle Rock. (R. Arnold.) 
PLEUROTOMA SANCTACRUCIS, new species. 
Plate XXXIII, fig. 7. 
DescriptionShell about 18 or 20 mm. in length, broadly fusi- 
form in shape; spire elevated cone-shaped, straight-sided ; apex mod- 
erately acute; whorls 6 or more, biangular, tabulated above and _ be- 
low, near suture, which is canal-like and very deeply and prominently 
impressed ; upper surface of whorl concave, side flat and sloping ex- 
actly with slope of spire, base flat and its plane practically perpen- 
dicular to the axis of the shell, surface sculptured by minute incre- 
mental lines and 1 or 2 obsolete revolving lines. Canal and aperture 
unknown; sinus as indicated by incremental lines corresponded in 
position to the upper angle of the whorl. 
Dimensions.—Of spire from which canal is lacking, length, 8 mm. ; 
latitude, 7 mm. 
Notes.—This peculiar species of which only the type is known is 
easily distinguished by its deep canal-like suture and the shape of the 
whorl the side of which is sloping with the slope of the sides of the 
spire, while the top and bottom are in planes practically perpendicu- 
lar eS the axis of the whole spire. Named for the Santa Cruz quad- 
rangle. 
Type.—Cat. No. 165445, U.S.N.M. (Locality No. 108.) 
Horizon.—San Lorenzo formation, Oligocene. 
Proc. N. M. vol. xxxryv-—08——24 
